update_unicode.sh: move it into contrib/update-unicode

As it's used only by a tiny minority of the Git developer population,
this script does not belong into the main Git source directory.

Move it into contrib/ and adjust the paths to account for the new
location.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/update-unicode/.gitignore

@@ -0,0 +1,3 @@
+uniset/
+UnicodeData.txt
+EastAsianWidth.txt

contrib/update-unicode/README

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+TL;DR: Run update_unicode.sh after the publication of a new Unicode
+standard and commit the resulting unicode_widths.h file.
+
+The long version
+================
+
+The Git source code ships the file unicode_widths.h which contains
+tables of zero and double width Unicode code points, respectively.
+These tables are generated using update_unicode.sh in this directory.
+update_unicode.sh itself uses a third-party tool, uniset, to query two
+Unicode data files for the interesting code points.
+
+On first run, update_unicode.sh clones uniset from Github and builds it.
+This requires a current-ish version of autoconf (2.69 works per December
+2016).
+
+On each run, update_unicode.sh checks whether more recent Unicode data
+files are available from the Unicode consortium, and rebuilds the header
+unicode_widths.h with the new data. The new header can then be
+committed.

contrib/update-unicode/update_unicode.sh

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+#!/bin/sh
+#See http://www.unicode.org/reports/tr44/
+#
+#Me Enclosing_Mark  an enclosing combining mark
+#Mn Nonspacing_Mark a nonspacing combining mark (zero advance width)
+#Cf Format          a format control character
+#
+cd "$(dirname "$0")"
+UNICODEWIDTH_H=$(git rev-parse --show-toplevel)/unicode_width.h
+(
+	if ! test -f UnicodeData.txt; then
+		wget http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
+	fi &&
+	if ! test -f EastAsianWidth.txt; then
+		wget http://www.unicode.org/Public/UCD/latest/ucd/EastAsianWidth.txt
+	fi &&
+	if ! test -d uniset; then
+		git clone https://github.com/depp/uniset.git
+	fi &&
+	(
+		cd uniset &&
+		if ! test -x uniset; then
+			autoreconf -i &&
+			./configure --enable-warnings=-Werror CFLAGS='-O0 -ggdb'
+		fi &&
+		make
+	) &&
+	UNICODE_DIR=. && export UNICODE_DIR &&
+	cat >$UNICODEWIDTH_H <<-EOF
+	static const struct interval zero_width[] = {
+		$(uniset/uniset --32 cat:Me,Mn,Cf + U+1160..U+11FF - U+00AD |
+		  grep -v plane)
+	};
+	static const struct interval double_width[] = {
+		$(uniset/uniset --32 eaw:F,W)
+	};
+	EOF
+)